Study of the theophylline content of single coated particles by gas chromatography/mass spectrometry

The aim of the present study was to determine by gas chromatography/mass sp ectrometry (GC/MS) the content uniformity of single theophylline microcapsu les of different particle size ranges. Microencapsulation was carried out i n a laboratory fluidized bed system using Eudragit L30D aqueous dispersion. Scanning electron microscopy was applied for the characterization of the s urface morphology of the prepared theophylline microcapsules of two differe nt particle size ranges. The theophylline content of single particles was d etermined by GC/MS analysis. It was found that the particle size of microca psules greatly influenced their theophylline content. The GC/MS analysis wa s successfully applied to indicate the changes in the content uniformity an d thus the interparticular coating distribution of single theophylline micr ocapsules in the presence of several excipients.